Petrophysical Evaluation and Reservoir Geometry Deduction of Idje Field, Offshore Niger Delta Nigeria

Abstract

The reservoir properties of the D-3 sandstone in Idje field of the Niger Delta region had been established. Petrophysical evaluation had been carried out as well as deducing the reservoir geometry. Idje field is an 8.4 km2 area between latitudes 4o31’49”N and 4o 33’23” N and longitudes 4o34’43”E and 4o36’17”E offshore Niger Delta in water depth of approximately 1000m on the continental slope. Well logs suites from ten wells comprising gamma ray, resistivity, neutron and density were obtained and analyzed. Petrophysical parameters were derived from which deductions and interpretations were made based on findings. Three sets of correlations were made on the E-W, NE-SW and NW-SE trends to ascertain the geometry of the reservoir. From the result, it was observed that the reservoir was a sedimentary dome possibly resulting from an underlying shale diapir. The log motif range from cylindrical shape with sharp base and top in the western portion to serrated shape in the eastern portion indicating a gradual transition from a slope channel fill (probably submarine canyon) in the proximal west to a distal deep marine slope towards the East. The Vshale range of 0.02 to 0.14 was shown to be for very clean sandstone in the west to slightly shaly sandstone in the east. The reservoir was shown to have a very good porosity and excellent permeability with average porosity value of 0.25 and an average permeability value of 3393.69m. Average hydrocarbon saturation of 48% was observed. Irreducible water saturation was 8% and the average water saturation across the hydrocarbon penetrated wells was 52%. Based on the aforementioned, water would be produced in the field alongside hydrocarbon and therefore possible measures for separation must be employed.